/*
 * Copyright (c) "Neo4j"
 * Neo4j Sweden AB [http://neo4j.com]
 *
 * This file is part of Neo4j.
 *
 * Neo4j is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package org.neo4j.graphdb.traversal;

import org.neo4j.graphdb.impl.traversal.AbstractSelectorOrderer;

public class AlternatingSelectorOrderer extends AbstractSelectorOrderer<Integer> {
    public AlternatingSelectorOrderer(BranchSelector startSelector, BranchSelector endSelector) {
        super(startSelector, endSelector);
    }

    @Override
    protected Integer initialState() {
        return 0;
    }

    @Override
    public TraversalBranch next(TraversalContext metadata) {
        TraversalBranch branch = nextBranchFromNextSelector(metadata, true);
        Integer previousDepth = getStateForCurrentSelector();
        if (branch != null && branch.length() == previousDepth) {
            return branch;
        } else {
            if (branch != null) {
                setStateForCurrentSelector(branch.length());
            }
        }
        return branch;
    }
}
